Switzerland is the most impressive place to visit IMO (Verbier if you can - fabulous resort), but it's also the most expensive (Austria generally being the cheapest, France and Italy somewhere inbetween).

Austria has the best aprés ski. Very friendly people and fairly inexpensive. St Anton is the place to go in Austria. Great skiing, great aprés ski. Zell and Kaprun offer a nice option (lots of tree runs at the lower levels in Zell and the glacier at Kaprun if snow is lacking).

Italy can be very good, depending on what you are looking for. Generally quiet slopes and beautiful scenery throughout (very rocky, lots of trees). Also the best mountain food anywhere. The Dolomites are beautiful but the resorts are generally lacking in terms of aprés ski. The Italians prefer to go home, get dressed up and mince around the towns later at night. People drive up from Milan, ski in the afternoons (but only if its sunny) and mostly go to hang out in the evenings.